Cryogenic storage facility



June 20, 1967 J SPARLJNG 3,326,011

CRYOGENIC STORAGE FACILITY Filed Oct. 21, 1965 JOSEPH 7. 5 412. ING

IN VEN TOR.

United States Patent 3,326,011 CRYOGENIC STGRAGE FAClLlTY Joseph T. Sparling, Vancouver, British Columbia, Canada, assignor to Cryogenic Enterprises Ltd, Vancouver, British Columbia, Canada, a corporation of Canada Filed (Pet. 21, 1965, Ser. No. 500,094 22 Claims. (Cl. 62-45) This invention relates to a storage facility especially designed for the containment and storage of cryogenic liquids, and is especially concerned with a cryogenic liquid storage facility which is disposed within the ground and which is provided with an insulation system resulting in low internal boil-off of cryogenic liquid, which eliminates danger from tank rupture and which can be constructed at relatively low cost.

Cryogenic liquid storage tanks presently in use. are of two general types, namely those which are constructed above the surface of the ground and those which are constructed in the ground. These facilities are employed for the storage of very low temperature volatile liquids, such as liquid air, liquid oxygen, liquid hydrocarbons,

which are often employed as refrigerants, liquid nitrogen, liquid hydrogen, liquid helium, and the like. Cryogenic liquid storage tanks which are constructed on the surface of the ground are usually in the form of a double wall vessel, the inner container holding the cryogenic liquid and the outer vessel or outer Wall being spaced from the inner vessel with an insulation medium positioned between the inner tank and the outer tank. These storage facilities are subject to certain disadvantages. In the first place, the construction of such storage facilities above ground are expensive and require the employment of costly supporting structures for the tank, and in some designs heating coils are required throughout the foundations. Further, leakage of vapors to the ambient atmosphere is difiicult to control, particularly when certain types of cryogenic liquids are being stored. Of particular importance any rupture of the tank will result in discharge of the cryogenic liquid to the surrounding area with resultant danger of explosion and fire where the cryogenic liquid is one which is combustible or which will form explosive mixtures with air, and also resulting in substantial economic loss Those cryogenic liquid storage facilities which are positioned below the surface of the ground also have certain disadvantages. In these facilities, it is usually necessary before excavating the hole to first freeze the surrounding ground to allow for excavation of a hole having substantially vertical walls. This is an expensive operation which often delays the completion of the project for approximately one year. In addition, such underground storage facilities are often relatively costly, both from the standpoint of the supporting roof construction and/or the cost of prefreezing the surrounding ground. Further, in the type of underground construction presently in use, cave-ins can occur. Also, in these types of construction there is a considerable amount of initial heat leak through the walls of the tank and into the surrounding ground. Further, in these prior art underground installations there exists the problem of product contamination, and there is also little assurance of positive measurement of the amount of' liquid contents in the storage facility.

The above noted disadvantages of presently constructed cyrogenic liquid storage facilities is obviated according to the invention by first providing a hole or excavation in the ground with sloping walls which permits easy excavation and will present no poblem with respect to soil heaving or ice-lensing. A suitable cryogenic liquid container or tank is placed in the excavation and is supported within the excavation on a suitable supporting structure,

Patented June 20, 196? preferably in the form of an elevated platform erected over the bottom of the excavation. In preferred practice, an inexpensive secondary insulation material is placed in the excavation and surrounding the cryogenic liquid container or tank, thus reducing evaporation through heat leak. A primary material preferably is provided over the top of the cryogenic liquid tank and over a portion of the excavation which is filled with the secondary insulation material, such primary insulation material also preferably being disposed between the container and the secondary insulation in the excavation. Such primary insulation protects chiefly against heat loss while providing increased efiiciency through reduction or elimination of convection currents on the exterior surfaces. A vapor and water impervious barrier layer of a suitable material is placed around the upper portions of the tank and over the pit and adjacent peripheral areas to provide further protection from the weather and the elements.

The resulting underground cryogenic liquid storage system is a completely inclosed facility providing minimum heat loss from the tank to the surrounding ground. The system is particularly designed for safety of operation and since the surrounding ground after a period of time will become frozen, any leakage of cryogenic liquid, for example, due to rupture of the tank, will be contained within the frozen pit and will be completely euclosed from above by the vapor impervious barrier provided around the tank and over the pit. Further, a relatively inexpensive tank supporting structure can be provided, substantially reducing the cost of construction of the facility.

The invention will be more clearly understood by reference to the description below of a preferred embodiment of the invention taken in connection with the accompanying drawing wherein:

FIG. 1 is a sectional elevational view illustrating a cryogenic liquid storage system according to the invention principles; and

FIG. 2 is a horizontal sectional view taken on line 22 of FIG. 1, showing certain details of construction of the storage facility of FIG. 1.

Referring to the drawing, in constructing a cryogenic storage facility according to the invention, a cryogenic liquid storage tank or container 10 is supported within an excavation 12 of appropriate size with respect to cross sectional area and depth so as to completely receive the cryogenic tank 10, with the top of the tank 10 approximately level with or slightly higher than the adjacent ground surface indicated at 14'. The cryogenic liquid storage tank 10 shown in the drawing is illustrated as being of cylindrical shape and accordingly an appropriately sized excavation 12 is dug with sloping walls as indicated at 16 and a relatively level or horizontal bottom indicated at 18, the excavation having a diameter larger than the diameter of the tank and a depth greater than the depth or height of the cryogenic storage tank 10. The excavation 12 can be conveniently and inexpensively made by means of standard earth moving equipment, such as by bulldozers, and the slope of the wall 16 of the excavation will depend on the particular soil conditions and on the greatest economy in operation of the earth moving equipment in making the excavation. t is particularly noteworthy that such excavation does not require expensive engineering or special soil conditions with respect to providing proper support for the side walls of the excavation.

As illustrated in the drawing, the cryogenic liquid storage container 10 can be of relatively simple construction and can be a single walled metal container of standard construction for storing cryogenic liquids. It will be understood that the container 10 can be equipped with proper fittings and appurtenances (not shown) usually employed for the operation of cryogenic storage vessels including means for providing adequate foam protection, and the like. The cryogenic liquid storage container, of course, can be of any suitable construction for storing the desired cryogenic liquid and can be of any desired shape. The container is positioned in the cavity 12 and is supported therein with its bottom 24 resting on a platform or deck mounted on a series of vertical supports which can be in the form of timber piling 22, the piles being suitably and rigidly embedded in the ground 14 below the bottom 18 of the excavation.

Adjacent to but spaced from the side wall 26 of the container 10, a retainer wall 28 is erected having a height exceeding to some extent the height of the tank wall 26. The retainer wall 28 completely surrounds the tank 10 and extends upwardly approximately to the level of the top of tank ,10 and'downwardly some distance below the bottom of tank 10 as indicated at 28 in FIG. 1. Retainer wall 28 can be formed of any suitable and preferably inexpensive material such as wood. Retainer wall 28 is supported in position on a circular base member 29 supported on piling 31 suitably embedded in the ground 14. The retainer wall 28 can be further supported to prevent buckling by suitable reinforcing members (not shown).

The space or volume between retaining wall 28 and the sloping sides 16 of the pit or excavation 12 preferably is filled with a dry so-called secondary insulation material, which is understood herein to denote any inexpensive form of dry bulk material which has insulating properties such as sawdust, straw, and the like, as indicated at 30. Similar secondary insulation material is also placed in a portion of the space or volume between the pit bottom 18 and the piling deck or platform 20, as indicated at 32. Depending upon the particular soil conditions, a water tight membrane 33 of a material. impervious to water such as plastic or a pitch or asphalt layer can be placed on the walls 16 and bottom 18 of the excavation between the soil 14 and the adjacent secondary insulation indicated at and 32.

In preferred practice a primary insulation material,.denoted herein as a material of high insulation characteristics and specifically designed and employed as an insulation material, such as perlite, preferably is placed, e.g., in water proof containers such as plastic bags, adjacent the inside of the retainer wall 28 in the space between it and the wall 26 of the tank, and on the surface of the secondary insulation material 32 in the space below the bottom of the tank 10, as indicated at 38 and 40 in FIG. 1. Other suitable primary insulation materials include, for example, silica aerogel (San-tocel) and diatomaceous earth. If desired, although not preferred, primary insulation can be positioned in the excavation at 30 and 32, and secondary insulation placed adjacent the inside of the retainer wall and also just below the container, as indicated at 38 and 40, or alternatively 30, 32, 38, and 40 can be composed entirely of secondary insulation, or entirely of primary insulation.

The container 10 is provided with a roof 42 supported in suitable and in conventional fashion, e.g., on a rafter 43 supported on a central column 45, and a cover 44 is provided to enclose the annular space 46 between the retainer wall 28 and the tank side wall 26, and a further extension or cover 48 is provided over a portion of the lip area beyond the retainer wall 28 and over the secondary insulation material 30 adjacent the retainer wall. Container roof 42 and the covers 44 and 48 preferably are provided thereover with a thick layer of additional primary insulation material such as perlite, as indicated at 50. If desired, although not preferred, the insulation material at 50 can be secondary insulation. The entire cryogenic liquid container 10 and the adjacent portions of the insulated pit below covers 44 and 48 are protected by a weather proof roof 52 which is preferably provided with a vapor and moisture impervious layer of material, such as pitch or asphalt, as indicated at 53, with access holes 54 provided in such roof. Roof 52 is supported on a rafter 55 which is centrally supported on an upper column extension 57 in turn supported on a crown plate 59 mounted on the top of column 45. A further vapor and weather proof barrier such as a layer of rubberized asphalt or other suitable material is provided as indicated at 56, and which extends in the form of a berm from the outer edge of the roof 52 or of cover 48, downwardly in sloping fashion over the secondary pit insulation material 30 and over a peripheral portion of the surrounding soil 14'. The extent of such barrier layer or pad 56 will de pend in large measure on particular soil conditions.

A cryogenic liquid inlet line 58 is provided to supply the container or tank 10 with cryogenic liquid. Cryogenic liquid is removed from tank 10 as desired, via the outlet line 62, employing a pump 60 for this purpose, or alternatively, if desired, a submerged pump (not shown).

It is accordingly seen that the cryogenic liquid tank 10 is suitably insulated to provide minimum heat leak to the adjacent ground 14 and to the ambient atmosphere above the tank by the system of insulation provided in the pit or excavation between the tank and the ground and between the top of the tank and the adjacent pit portions. After the cryogenic liquid has been stored in tank 10 for a period, the surrounding soil 14 adjacent to the excavation will become frozen, and the attainment of this condition will further tend to reduce heat leak from the tank The cryogenic liquid storage system of the invention has a number of advantages and improvements over prior art systems. Thus, in view of the unique insulation concepts of the invention, substantially less loss of cryogenic vapors is experienced. Heat leak can be controlled readily by the particular design of insulation according to the invention, so that there is no necessity for excess energy loss where a predetermined amount of vaporization of cryogenic liquid is desired. The system is particularly designed for safe operation and for ease in fire prevention, and the frozen earth adjacent the secondary insulation 30 and 32 in the excavation will contain any cryogenic fluid which is discharged in the event of any rupture of the submerged storage tank. Further, such contingencies as noted above are minimized since the system design provides a free standing tank not exposed to any external load, reducing the danger of structural failure and tank rupture.

A particular advantage of the invention system is that the tank can be placed in any type of soil and no prefreezing of the ground adjacent to the excavation prior to installation of the tank is required, which freezing operation in conventional underground cryogenic storage installations may require from several months to a year before construction of the underground facility can be commenced. The invention storage system on the other hand can be rapidly constructed and less initial heat loss is experienced. The positive enclosure over the storage tank and excavation excludes possiblecontamination and permits definite quality and quantity control of the stored cryogenic liquid at all times. The entire composite system of tank, excavation and insulation is effectively protected from external weather elements by a vapor impervious barrier, and the entire system is well drained of surface water. During excavation and until freezing takes place, underground water can be eliminated or controlled by means of well points.

It will be understood that various modifications and adaptations of the invention can be made by those skilled. in the art without departing from the spirit of the invention, and accordingly the invention is not to be taken as limited except by the scope of the appended claims.

I claim:

1. A cryogenicliquid storage facility which comprises an excavation, a container for a cryogenic fluid, said container having a bottom and a side wall, means supporting the bottom of said container in said excavation, with the side wall and bottom of said container spaced from the adjacent walls and surfaces of said excavation, a nonrigid first insulation material in the space between said container side wall and the adjacent walls of said excavation, said side wall being otherwise essentially unsupported, said insulation material also disposed on the bottom of said excavation and below said container, and a second insulation material positioned over said container and over at least a portion of said excavation.

2. A cryogenic liquid storage facility as defined in claim 1, including a retainer wall positioned in said excavation about said container, said retainer wall being spaced from the adjacent wall of said container and from the adjacent walls of said excavation, said first insulation material filling the space between said retainer wall and the adjacent walls of said excavation, said second insulation material positioned over said container and over the annular space between said container and said retainer wall.

'3. A cryogenic liquid storage facility as defined in claim 1, said first insulation material being a secondary insulation material and said second insulation material being a primary insulation material.

'4. A cryogenic liquid storage facility as defined in claim 2, including insulation material disposed between said retainer wall and the adjacent wall of said container and also between said insulation material in the bottom of said excavation, and the bottom of said container.

5. A cryogenic liquid storage facility as defined in claim 2, said first insulation material being a secondary insulation material and said second insulation material being a primary insulation material, and including a primary insulation material disposed between said retainer wall and the adjacent wall of said container and also between said secondary insulation material in the bottom of said excavation, and the bottom of said container.

6. A cryogenic liquid storage facility as defined in claim 3, including a primary insulation material placed over said secondary insulation material in the peripheral area of said excavation just beyond said retainer wall.

7. A cryogenic liquid storage facility as defined in claim 2, said first insulation material being a secondary insulation material and said second insulation material being a primary insulation material, and including a primary insulation material disposed between said retainer wall and the adjacent wall of said container and also between said secondary insulation material in the bottom of said excavation, and the bottom of said container, and a primary insulation material placed over said secondary insulation material in the peripheral area of said excavation just beyond said retainer wall.

8. A cryogenic liquid storage facility as defined in claim 1, including a vapor impermeable barrier layer positioned over said first insulation material in the peripheral area of said excavation, and covering said area at least to the outer periphery of said excavation.

9. A cryogenic liquid storage facility as defined in claim 1, including a water impervious organic layer between the soil and the adjacent insulation in said excavation.

10. A cryogenic liquid storage facility which comprises an excavation having sloping walls, a container for a cryogenic fluid, a deck for supporting said container, pilings supporting said deck and embedded in the ground at the bottom of said excavation, said deck being positioned above the bottom of said excavation, said container mounted on said deck within said excavation, the upper portion of said container being approximately at the level of the ground adjacent said excavation, a retainer wall positioned in said excavation and surrounding said container, said retainer wall being spaced from the adjacent wall of said container and from the adjacent sloping wall of said excavation, said retainer wall having a height somewhat greater than the height of said container and extending downward a distance below said container and extending upward approximately to the level of the top of said container, a secondary insulation material filling the space between said retainer wall and the adjacent wall of said excavation, said secondary insulation material also disposed on the bottom of said excavation and partially filling the space below said container, a rimary insulation material disposed adjacent said retainer wall and between said wall and the adjacent wall of said container, and also disposed between said secondary insulation material at the bottom of said excavation and said deck, a cover over said container, a cover over the annular space between said container and said retainer wall and extending over the adjacent lip of said excavation beyond said retainer wall, a primary insulation material positioned over said covers, and covering said container, said annular space and the peripheral area just beyond said retainer wall, a roof positioned over said covers and over said primary insulation material thereon, and a vapor impermeable barrier layer positioned over said secondary insulation in the peripheral area beyond said last mentioned cover, and overlying said peripheral area and said secondary insulation in said excavation.

11. A cryogenic liquid storage facility as defined in claim 10, said secondary insulation material disposed on the bottom of said excavation partially filling the space below said container approximately up to the lower edge of said retainer wall, and including a weather proof barrier layer over said roof, said vapor impermeable barrier layer positioned over said secondary insulation in the peripheral area beyond said roof slopping downwardly and covering said peripheral area and said secondary insulation and also the soil adjacent the periphery of said excavation.

12. A cryogenic liquid storage facility as defined in claim 10, including a water impervious membrane covering the bottom of said excavation between the soil and the adjacent secondary insulation thereon.

13. A cryogenic liquid storage facility as defined in claim 3, wherein said secondary insulation material is sawdust and said primary insulttion material is perlite.

14. A cryogenic liquid storage facility as defined in claim 10, wherein said secondary insulation material is sawdust and said primary insulation material is perlite.

15. A cryogenic liquid storage facility as defined in claim 8, wherein said vapor impermeable barrier layer is an asphalt layer.

16. A cryogenic liquid storage facility as defined in claim 10, wherein said vapor impermeable barrier layer is an asphalt layer.

17. A cryogenic liquid storage facility which comprises an excavation, a container for a cryogenic fluid, means supporting said container in said excavation spaced from the adjacent walls and surfaces of said excavation, a first insulation material in the space between said container and the adjacent walls of said excavation, a retainer wall positioned in said excavation about said container, said retainer wall being spaced from the adjacent wall of said container and from the adjacent walls of said excavation, said first insulation material filling the space between said retainer wall and the adjacent walls of said excavation, said first insulation material also disposed on the bottom of said excavation and below said container, a cover over said container, a cover over the annular space between space between said container and said retainer wall, a second insulation material positioned over said covers, and a roof positioned over said covers and over said second insulation material thereon.

18. A cryogenic liquid storage facility which comprises an excavation, a container for a cryogenic fluid, means supporting said container in said excavation spaced from the adjacent walls and surfaces of said excavation, a first insulation material in the space between said container and the adjacent walls of said excavation, a retainer wall positioned in said excavation about said container, said retainer wall being s aced from the adjacent wall of said container and from the adjacent walls of said excavation, said first insulation material filling the space between said retainer wall and the adjacent walls of said excavation, said first insulation material also disposed on the bottom of said excavation and below said container, a second insulation material positioned over said container and over the annular space between said container and said retainer wall, said first insulation material being a secondary insulation material and said second insulation material being a primary insulation material, and including a primary insulation material disposed between said retainer Wall and the adjacent wall of said container and also between said secondary insulation material in the bottom of said excavation, and the bottom of said container, a primary insulation material placed over said secondary insulation material in the peripheral area of said excavation just beyond said retainer wall, a vapor impermeable barrier layer positioned over said insulation material in the peripheral area of said excavation beyond said retainer wall, and covering said area at least to the outer periphery of said excavation.

19. A cryogenic liquid storage facility as defined in claim 18, said barrier layer being in the form of a berm sloping downwardly toward the outer periphery of said excavation, and extending partially over the soil adjacent the outer periphery of said excavation.

20. A cryogenic liquid storage facility which comprises an excavation having sloping walls, a container for a cryogenic fluid, said container having a bottom and a side wall, means supporting essentially only the bottom of said container in said excavation, with the side Wall and the bottom of said container spaced from the adjacent walls and surfaces of said excavation, a first nonrigid insulation material in the space between said container and the adjacent walls of said excavation, said first insulation material being disposed adjacent said sloping walls of said excavation, and a second insulation material positioned over said container and over at least a portion of said excavation.

21. A cryogenic liquid storage facility as defined in claim 20, wherein said first insulation material is sawdust.

22. A cryogenic liquid storage facility as defined in claim 20, wherein said first insulation material is sawdust and said second insulation material is perlite.

References Cited UNITED STATES PATENTS 2,437,909 3/1948 Cooper 6245 2,520,883 8/ 1950 Kornemann et al 62--45 2,999,366 9/1961 LaFave et al 62-45 3,151,416 10/1964 Eakin et al 62-45 3,196,622 7/1965 Smith et al. 62-45 3,205,665 9/1965 Van Horn 6245, 3,249,251 5/1966 Nachshen 610.5

LLOYD L. KING, Primary Examiner. 

1. A CRYOGENIC LIQUID STORAGE FACILITY WHICH COMPRISES AN EXCAVATION, A CONTAINER FOR A CRYOGENIC FLUID, SAID CONTAINER HAVING A BOTTOM AND A SIDE WALL, MEANS SUPPORTING THE BOTTOM OF SAID CONTAINER IN SAID EXCAVATION, WITH THE SIDE WALL AND BOTTOM OF SAID CONTAINER SPACED FROM THE ADJACENT WALLS AND SURFACES OF SAID EXCAVATION, A NONRIGID FIRST INSULATION MATERIAL IN THE SPACE BETWEEN SAID CONTAINER SIDE WALL AND THE ADJACENT WALLS OF SAID EXCAVATION, SAID SIDE WALL BEING OTHERWISE ESSENTIALLY UNSUPPORTED, SAID INSULATION MATERIAL ALSO DISPOSED ON THE BOTTOM OF SAID EXCAVATION AND BELOW SAID CONTAINER, AND A SECOND INSULATION MATERIAL POSITIONED OVER SAID CONTAINER AND OVER AT LEAST A PORTION OF SAID EXCAVATION. 